05 Lly Oil Pressure Weirdness

whitesnake01 · November 7, 2010

This past weekend I had something weird happen to my 05 truck with an LLY in it. 131K. After towing for about 2hrs, I noticed that the oil pressure started to nudge up a bit. After a while it sat at 90PSI. And it kept going, slowly approaching 120PSI. Engine temp was fine. I pulled over, shut it off, and brought it back on again. The needle did not sweep back to 0 before going up. Instead, it swept back to 90PSI and then blew past 120PSI and basically went past the marker. I pulled a few more miles until I got to the campsite. Checked the oil level. Just fine. No smell of diesel in the fuel. I called for an appointment with the dealer.

Next, day, fired it up. Pressure still very high. Over the next couple of days, the needle would gradually work its way back to near normal. By the time my appointment with the dealer came up, the range seemed completely normal again. They could not find anything wrong with it.

What might it be?

- faulty sensor

- chafed wires

- bad connctor(s)

Anyone else seen this?

Thanks

jro909 · November 7, 2010

sounds like a faulty guage or sensor...i can't see pressure going that high on a warm engine

dewfpo · November 7, 2010

Or bad oil filter or sticky bypass valve.

DEWFPO

Prokopchuk_9 · November 7, 2010

bad by pass valve or a bad gauge man...nothing expensive happened to me before cept mine blew the dipstick and spayed oil ALL over under the hood

whitesnake01 · November 7, 2010

How would you recommend that I go about fixing it? Right now the pressure is back to normal and that is frustrating. I do not believe in self healing trucks. Should I wait until the symptom comes back? Seems like I can just change the oil (which is Mobil-1) and the filter (AC Delco). If it comes back, it seems unlikely do be the oil filter. What do you think?

8.1HD/ALLISON · November 7, 2010

How would you recommend that I go about fixing it? Right now the pressure is back to normal and that is frustrating. I do not believe in self healing trucks. Should I wait until the symptom comes back? Seems like I can just change the oil (which is Mobil-1) and the filter (AC Delco). If it comes back, it seems unlikely do be the oil filter. What do you think?

Sounds like a cluster issue to me. They had all kinds of problems with clusters. Mostly speedos, but some of the other guages too.

dewfpo · November 7, 2010

In my opinion, the cheapest, easiest thing to do is replace the filter with a new one. If it never happens again, you've found your problem. If it comes back, then I'd look at the sensor first then the gauge. Typically bad sensors or gauges will repeat the problem. Most all the bad gauges or sensors I have seen are either stuck at one pressure, ZERO or MAX either all the time or randomly. They normally don't behave as you have described in my experience. A bad pressure regulator could behave that way if it were gummed up badly but it sounds like you maintain your engine well so that shouldn't be a problem. I have seen filter media fail and cause pressure issues.

Hopefully a filter change will solve the problem.

DEWFPO

markw8 · November 7, 2010

On my 01 Vette, if the sender fails it pegs the guage.

Mark

whitesnake01 · November 8, 2010

I replaced the oil and filter today. I'll update this thread as I learn more. I'll keep the old filter, in case the problem went away with the new one. Thanks for all your helpful tips. When the problem surfaced it was a bit colder (around freezing) than we have now. So if this is temperature related, it might show again once it gets colder again.